1. Field of the Invention
The present invention generally relates to a picture file system which records and reproduces a multiplicity of picture data.
2. Description of the Related Art
A large-capacity magnetic disk system and an optical disk system have been recently developed with the advancement of high-density recording techniques. The optical disk system, in particular, which has a large storage capacity, has enabled the filing (storage) of a large number of pictures, which has been so far impossible. When it is desired to retrieve a desired picture from a picture file system having a large quantity of picture data stored therein, the desired picture itself has been so far retrieved on the basis of the name or contents description applied to the desired picture. In this case, however, if a picture or pictures similar to the desired one are also filed in the picture file system, there is a high probability another and wrong picture will be read out. Meanwhile, when a person different from the file creator wishes to retrieve the file, it is difficult to grasp the correct contents of a desired picture on the basis of only the name and contents description of the picture and thus the retrieval disadvantageously becomes time-consuming. As a means for overcoming such disadvantage, there has been proposed a known picture file system wherein only characteristic parts are extracted from picture data to be recorded to obtain a reduced picture data, and the reduced picture and its original picture are previously stored at the picture storage time. At the retrieval time, a plurality of such reduced pictures are read out and displayed at the same time, retrieval being carried out on the basis of the displayed reduced pictures (refer to JP-A-61-264448). With such a picture file system, at the time of displaying a multiplicity of reduced pictures on a display screen for picture retrieval, reduced picture data having the same key word or a similar picture name and contents description are sequentially accessed and reproduced one after another and are written into a display frame memory. In this case, if the reduced picture data are scattered on a recording medium, it is necessary to previously manage the address data of each reduced picture data and the directory retrieval operation and the address retrieval operation of the recording medium are required for each reduced picture data, which results in the access time becoming large and thus the time needed to display a picture for retrieval becomes large. In particular, the access time of an optical disk, for example, having a diameter of 20 cm is as large as about 1 second, in which case, when a multiplicity of reduced pictures are to be displayed on a display screen at the same time for the purpose of improving the retrieval efficiency, the time necessary for the displaying of the multiplicity of reduced pictures becomes unfavorably large and the response performance of the picture file system is disadvantageously deteriorated.